I went out to my pond this morning and found one of my fish sideways in one of my plants. Tried holding it and putting it where the aerator is but didn't seem to help and started checking it out and saw this black on its scale. Since I know nothing about what diseases might affect them I decided to remove it since I knew it was going to die but wanted to come here and see who could tell me what it might be and how I can prevent it. All of my pond tests have been excellent and we are having babies so was feeling really good and then this happened. I added salt to the pond after this in hopes this might help and do most of you keep your salinity level consistent all year? Thanks in advance...Julie